Screw-coupling.



G. SGHUHMANN. SCREW COUPLING. AfPPLIiOATION FILED MAR.15, 1909.

929,027. Patented July 27, 1909.

`GEORGE SCHUHMANN, or READING, PENNSYLVANIA.

l seREiv-COUBLING.

To alt 'whom zt 'may concern:

Be 1t known that I, GEORGE SCHUHMANN, a

Specification bf Letters Patent. Application led March 15, 1.90.9.Serial 4No. 483,448.

citizen of the United States, and a resident of l the city of Reading,in the countyv of Berks and State of Pennsylvania, have invented certainnew and useful Improvements in Screw-Couplings, of whichthe followingis'a specification.

My invention relates to 'screwcouplings generally, but more particularlyto those em'- ployed in connecting oil well tubingand the ke, in whichthe couplings are subjected to. l special strains due to the heavyweight de-.

. pending from them and lsimultaneous vibratory or jarring action,` theeffects -of both of which strains are ordinarily concentrated at the endof the threads as the weakest points in the connected tubing.

'Ihe object of my invention is to provide in a simple and effective wayfor eliminating these points of weakness,.for supporting the screwthreaded portion of the tubing so as to prevent. injurious vibratingaction, and for maintaining these conditions and a uniform strain uponthe couplingr sleeve notwithstanding frequent screwing and unscrewingofthe parts.

y Couplings have heretofore been made in which the male and femalemembers have each been provided with a vanishing thread cut to agradually-reducing depth on a conical surface so that the bottoms ofsuccessive j convolutions lie in one tapering line while the tops of thethreads lie in-a line of'different taper. 1 This construction not onlyinvolves the cutting of a s ecial form of thread upon both the male anfemale memberarequiring more than ordinary labor and skill to provide ia uniform contact of the threads throughout when the parts are in normalengagement, but owing to such differing tapers the repeated rescrewingtogether of the parts pro-- i d'uces unequally distributed strains inthe coupling.

My invention consists in forming an ordinary tapering thread in thefemale member of the coupling, and a corresponding ordinary thread upontheconical portion of the male member gradually vanishing upon theadjoining cylindrical ortion ofthe latter` with the bottom of the treadthroughout lyingl on a straight line'parallel with the line joiningthe tops of the full threads; a uniform taper -of the threads upon bothmembers belng maintained asusual, and the connecting fermented my 27,1909.

male member being extended beyond the conical portion-of the male memberso that the to s of its threads engage the vanishing .threa upon thecylindrical body of the tube, thereby reinforcingthe latter up to theuncut portion of the tube, as hereafter fully described and specificallypointed out.

The drawing is a diagrammatic cross-sectional view of a screwthreadedpipe. coupling .embodying my invention, the uniform taper of the threadsbeing somewhat exaggerated.

. 'I he sleeve or female member a of the coupling, is providedinteriorly, as /usualf with a full conical thread b, extending its fulllength as shown though obviously the Yunthreaded body of the sleeve maybe projected beyond the threaded portion, if desired, to guard the-endof the thread as is commonly done.

T he tube end or male member c `of the coupling, is also provided asusual with a full conical thread d corresponding in form and taper withtheinterior thread b of the female member; but said thread, instead ofending more orlessabruptly with the bottom of its end convolution belowthe c lind'rical surface .e of the body of the tube, 1s continued asavanishing thread formed upon the cylindrical 'body of the tube until thevanishing bottom f of the thread, lying always on the straight line gparallel with the line h joining the tops of the full thread, is blendedinto the cylindrical surface e of the tube.

r[he threaded female member a, when screwed upon the malemember c, isadapted to effect a perfect thread-contact when. the end of the membera, is projected beyond the conical portion of the member c so as to in-vclose the adjoining cylindrical portion of the tube with the to portionsofthe end convolutions of its t read engaging the vanishing thread onthe cylindrical tube'body; so that the latter is rigidly supported bythe female member fully up to the uncut portion thereof whereby anyvibratory action upon the weakenedv thread portion is prevented; while"at the same time the full tensile strength of the unthraded'tube isretained to withstand longitudinal strains. v A single uniform taperbeing employed as usual upon both engaging-members, not only is aperfect engagement of` the threads strains ter how frequently the jointmay be unscrewed and rescrewed; any Wear of the .threads being uniformlytaken up by the l thread upon the male member, the length of thc femalemember is made sufficiently greater than is ordinarily required topermit of `its fully covering said vanishing thread. But my improvementinvolves no change in the usual size or structure of the pipe member endsuch as enlarging the same; or any objectionable departure from theordinary thread-cutting operation or the thread-cutting tools commonlyemployed; yet it effectively secures the desired objects of maintainingthe tensile strength of the pipe scction and eliminating the usualvibra'tory strains at the terminus of the thread, while insuring auniform t of the threads how? ever frequently the connections may bescrewed and unscrewed.

What I claim is:-

1. In a screw coupling a male member having a full screw thread on aconical surface vanishing on an. adjoining cylindrical surface,the'bottoms of the thread convolutions vthroughout being on a straightline parallel With the tops of the full threads.

p 2. A screw coupling comprising a male member having a full screwthread 0n a conical surface vanishing on an adjoining cylindricalsurface, the bottoms of the thread convolutions throughout being on astraight 1 line parallel with the tops of the full threads, and a femalemember having a screw thread on a conical surface, the top portion onlyof which thread enga es the vanishing thread on the cylindrica surfaceof the male member.y

In testimony whereof, I affix my signature, in the presence of twowitnesses.`

` GEORGE SCHUHMANN. Witnesses:

W. G. STEWART, D. M. STEWART.'

